Orally administered drugs are provided to the patient in many dosage forms, including solid forms such as capsules, caplets or tablets and liquid forms such as solutions, emulsions or suspensions. Pharmaceuticals administered in solid form are usually intended to be swallowed whole. The disagreeable taste of the drug is generally not of concern when formulating swallowable dosage forms, because the pharmaceutical's taste can be easily masked with an exterior coating.
Children, older persons, and many other persons including disabled or incapacitated patients often have trouble swallowing tablets or capsules. In these situations, it is desirable to provide the drug either in a chewable solid form or a liquid form. For many patients, including pediatric and geriatric patients, a liquid oral dosage form is preferred over a chewable dosage form. A liquid dosage is especially preferred for this class of patients because of the ease with which it may be swallowed. Additionally, patients may be more inclined to comply with their medication instruction if the dosages are easier to ingest.
However, a common problem associated with liquid pharmaceutical dosage forms is the often disagreeable taste of a drug that may manifest itself when the drug is in the liquid dosage form. Sometimes, the taste of the drug in the dosage form may be overpowered by adding sweeteners or flavoring agents to the formulation. These agents mask the bitter or unpleasant taste of drugs. However, these agents are not totally effective in concealing the unpalatable taste of the pharmaceutical.
Liquid suspension dosage forms have stability problems associated with maintaining the drugs in suspension. Poorly formulated liquid pharmaceutical suspensions allow the drug to settle out as a sediment and may not properly redisperse, thereby affecting the therapeutic concentration of drug in the suspension. This may result in underdosing or overdosing of the patient, which may seriously compromise the patient's recovery.
If the liquid dosage form is a combination product containing both dissolved and suspended solid pharmaceutical actives, one active must remain suspended and the other active(s) must be uniformly distributed throughout the composition to ensure proper dosing. Additionally, the pharmaceutical suspension should be readily pourable so that the dosage is easy to administer. The requirement that a pharmaceutical suspension is readily pourable effectively places an upper limit on the viscosity of the suspension. This limitation also indirectly limits the amount of pharmaceutical actives that the suspension will suspend.
In view of these difficulties, it would be desirable to develop a ready-to-use pharmaceutical suspension, especially for combination products containing both dissolved and suspended solid actives, with a high degree of stability and good taste-masking characteristics. Therefore, there exists a need for a liquid dosage form that minimizes sedimentation of the suspended active ingredient, provides uniform distribution of the dissolved active ingredient and has a palatable taste.
The present invention provides a stable aqueous suspension for formulations containing suspended acetaminophen and at least one additional pharmaceutical active, which when combined with sweeteners and flavoring agents, provides a palatable liquid dosage form. This dosage form is also physicochemically stable and especially well suited for both geriatric and pediatric applications.